The present invention relates to a method for determining the position of the drive mechanism of an electric machine, such as a motor, from the current that is supplied, whereby for the reliable operation, the determination of the position of the drive mechanism is effected over two paths or channels that are independent of one another, and thereafter the two position values are combined and are cross checked with respect to a safe manner of operation, such as maintenance of a safe speed or safe positioning of the drive mechanism, including the following method steps:                determination of the position of the drive mechanism in one channel by measuring the three-phase current of the machine, subsequently        converting the measured values of this three-phase current to a current space vector        calculating the angle of the current space vector within one electrical revolution, and        determining the position of the drive mechanism (rotor).        
Such a method is already known from DE 101 63 010 B4.
The known method has the drawback that at low speeds and/or low loads, the amplitude or length of the current space vector is about 0, and due to the fluctuation of the measured values in all possible directions due to the super imposed speed and position regulation, which adversely affects the measurement of the position and later the calculation e.g. of the speed due to the position alteration, the measurements show large errors with regard to position and speed.
It is an object of the present invention to ensure that the direction of the current space vector can be determined precisely, even at low speeds and low loads.